1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and a program.
2. Description of the Related Art
The digitization of information is advancing in recent years, and systems are increasingly prevalent wherein paper documents are not stored as-is, but instead digitized by scanning using a scanner or similar device, with the resulting electronic data being stored or sent to another apparatus. In order to reduce transmission costs, high compressibility is demanded of digitized document images. Also demanded are reusability enabling partial editing of document images, as well as high image quality wherein image quality is not lost after enlarging or reducing document images.
However, when text regions and photo regions are mixed within a document image, applying compression suited to text regions results in good image quality but with a lower compression ratio. Meanwhile, applying compression suited to photo regions results in a high compression ratio, but with less-readable text. Consequently, the related art divides digitized document images into text regions and photo regions, and converts the text regions into vector data, where reusability and high image quality are emphasized. The related art then uses JPEG to compress the remaining photo and other regions that cannot be easily reproduced by vectorization, and then synthesizes and outputs the compressed results for the respective regions. In so doing, the related art realizes highly compressible and reusable document images with high image quality (see Japanese Patent Laid-Open No. 2004-265384).
In many cases, a region enclosed by a large frame taking up either approximately a fourth or over half of the total area of a document image (hereinafter also referred to as the large frame region) contains within it many graphics vectorization regions. Herein, such graphics vectorization regions are graphics regions targeted for vectorization.
When a plurality of graphics vectorization regions overlap, handling the partial overlaps of the target regions becomes difficult if each of the plurality of target regions is separately processed as a graphics vectorization region. Consequently, in such cases, the plurality of graphics vectorization regions are synthesized into a large, all-containing region. Vectorizing such a large, synthesized graphics vectorization region is easier.
However, if the entire plurality of graphics vectorization regions within the large frame region are treated as a single graphics vectorization region, then the region to be vectorized becomes too large, and the time required to process each image becomes extremely long. In order to resolve such increases in processing time, it is conceivable to reduce the graphics vectorization region before vectorizing. However, in this case, the image quality is degraded for the comparatively small graphics vectorization region contained within the large frame region. Furthermore, when enlarging the graphics vectorization region, insufficient memory or limitations on processing time may result in only a portion of the graphics vectorization region within the large frame region being processed.
In light of the foregoing problems, it is desirable to provide an image processing apparatus able to shorten processing time.